The episode begins with a man arriving home. He goes to the bar and pours himself a drink, completely unaware of the fact that there is stranger sitting on a couch with a laptop. The stranger clicks a button, and the man has an attack. With the click of another button, he man feels better. The stranger makes the man aware of his presence and tells him that he is able to control his pacemaker through his laptop. He explains that every pacemaker has a unique code and if one knows that, he can make the pacemaker do all sorts of things. The man asks the stranger what he wants. The stranger tells him to cast his ballot, vote to revoke. The man does the same. ..Read the full recap
(Watson comes down the stairs after hearing Sherlock scream, and finds him struggling with a straight jacket.)
Watson: You dislocated your own shoulder because...?
Sherlock: Are you thick?
Watson: Am I thick? You're the one stuck in a straight jacket.
(After telling Sherlock to stay quiet about what he sees there, Moran kills a guard.)
Moran: (While being hauled off) Too late boys! No medic needed! No medic. (Turns back and signals Sherlock to be quiet, then starts singing loudly.) Too late! "Too late", will be the cry when the lady with bags passes by. Sherlock's up and Sherlock's down, but he always wears that sacred frown.
(After Sherlock lies to Gregson, Watson confronts him about it.)
Watson: Last time you lied about Moran you planned to torture and kill him.
Sherlock: I was quite honest about my intentions.
Watson: What if these impulses get triggered again?
Sherlock: You are no longer required to play hall monitor to my impulses.
(Watson isn't convinced, but Sherlock explains that they're looking for another of Moriarty's assassins.)
Sherlock: I'm now more and more convinced that we are in pursuit of one of his agents. He does the same kind of work Moran does, but in a very different way. This man specializes in murders that do not appear to be murders at all. Moran was the sledge hammer, our current query is the scalpel.
(Sherlock and Watson watch a video and plan their next move.)
Sherlock: If I was a sociopath and I wanted to stop anyone from taking too close a look at my murderous transaction I would remove Mrs Taggart from the chess board.
Watson: We need to warn her.
Sherlock: We will do no such thing. Our mission is to study this woman, observe her in her natural habitat. The best way to keep this woman safe is to find out how to kill her.
(Sherlock interrogates the assassin.)
Gottlieb: One more thing. I know you, your face. I was doing some work for him in London a few years ago. I got a text with your picture. You were dabbling in drugs. I had an accidental overdose lined up for you.
(Sherlock gets frustrated over decoding the text.)
Sherlock: Thank you! Watson, you know, some people without possessing genius have a remarkable way of stimulating it.
Watson: Oh, an insult and a boast.
The idea that pacemakers could be "hacked" is a very real possibility, and has led to conspiracy theories surrounding the death of an "Ethical Hacker". Barnaby Jack, who was a reputable "hacker", was scheduled to demonstrate the vulnerabilities at the Black Hat security conference in 2013, but died days before he could share what he had found. After withholding his findings, a coroner's report showed a cocktail of drugs in the man's system. It should be noted that the episode predates the death of Barnaby Jack, by a few months.